It shows that the --depth option will define WC-depth for those not exist in
the wc yet (aka omitted-items). I wrote a test case for it, which is
gracefully passed. I expect this behavior is consistent in other subcommands
and thus add a verify_depth(None, "files", new1_path) to check it in the
"add_tree_with_depth_files" test case. To my surprise, the depth of new
added
directory is still infinity. What do you think about this? Do I made a wrong
assumption or is it actually a bug?

Anyway, I suggest the description of --depth option in the commandline help
messages be improved to notify this behavior, at least for the checkout,
update and switch commands. The new description should looks like this: